FIG 3.

β-Lactamase-expressing E. coli evolves resistance more rapidly to high-amoxicillin/low-clavulanate compositions. (a) The growth of the ancestral strain in different drug environments is affected by the dose strength (shown by color) of the drug combination but is not significantly affected by the amoxicillin proportion of the drug combination. (b) Adaptation of lines selected at high dose strengths of various amoxicillin proportions (shown by color) shows that adaptation to low amoxicillin proportions is slower (the data points for passage 1 are a repeat of the high-dose data for panel a). (c) Control evolution lines are again affected by the dose strength of the drug but are not significantly affected by amoxicillin proportion. (d) The growth of drug-selected lines evolved for six passages in their selection environment is higher for strains evolved at high-amoxicillin/low-clavulanate compositions.